An Overview of Embryonic Stem Cell Research

Embryonic stem cells are undifferentiated cells that show promise in the treatment of heart disease, cancer, spinal cord injuries, diabetes and Parkinson's disease. For example, if stem cells are introduced into a patient's heart after a heart attack, they will migrate to the site of the damage, proliferate, and differentiate into new cardiomyocytes, or heart muscle cells. Stem cells injected into the brains of Parkinson's patients can become healthy neurons. Neural stem cells can even track and destroy migrating cancer cells in brain tumors. Research on the applications of stem cells to repair damaged tissue has given rise to a new medical specialty known as regenerative medicine.

Human embryonic stem cell research is a controversial topic because the cells are derived from human embryos called blastocysts. To obtain stem cells from the inner cell mass of the blastocyst, the embryo must be disassembled. The component cells are then grown in culture. A blastocyst is a microscopic five-day-old sphere of cells, not recognizable as human fetus. However, it is a human embryo, and the use of human embryos for medical experiments and trials is the heart of the debate.

Former United States President George W. Bush and other social conservatives argue that it is not right to destroy a potential human life, even to benefit others. The majority of people in the pro-life movement view killing an embryo as morally equivalent to murder, but scientists and patient's rights advocates do not agree that an embryo is entitled to full human rights. Advocates of stem cell research, such as former U.S. First Lady Nancy Reagan and actor Michael J. Fox, focus on the help that stem cell research can bring to suffering patients.

Efforts are underway to develop alternative sources of stem cells. Human somatic stem cells, or adult stem cells, can be harmlessly isolated from umbilical cord blood as well as adult tissues and organs. Adult stem cells appear to have many of the same regenerative properties of embryonic stem cells.

Angiogenesis:The development of new blood vessels. In diseased hearts, angiogenesis is stimulated by the introduction ofstem cells.

Cell Lines:Groups of cells produced in a laboratory from common ancestry. The cells within a cell line are usually genetically identical to one another.

Dopamine-Producing Nerve Cells:Certain neurons in the brain produce dopamine, a neurotransmitter that sends signals from one cell to another. Dopamine is involved in movement and experiencing pleasure; because of this, Parkinson's disease patients may display involuntary movements and suffer from depression.

Parkinson's Disease:A degenerative disorder of the brain caused by the death of cells that produce dopamine. Parkinson's sufferers often have tremors and uncontrolled movements that can make speech difficult. The disease may progress to dementia in its later stages. Actor Michael J. Fox is a stem cell research advocate who suffers from Parkinson's disease.

Undifferentiated Cells:Unspecialized cells with the potential to become one of a variety of cell types. If grown with a certain type of cell they often differentiate, or mature, to become that type of cell. Such cells are also described as pluripotent.